This seeks to utilize social network methodology to examine network characteristics as mediating variables between alcohol consumption and HIV risk behaviors in STD clinic clients in Baltimore, Maryland. The study is an extension of our previous research, in which we found that social network characteristics were associated with HIV risk behaviors in a sample of injecting drug users. Previous research on the relationship between alcohol use and HIV sexual risk behavior has produced inconsistent results. We hypothesize that social support factors may mediate the relationship between alcohol use and risk behavior. Through social network analysis we will examine protective and risk characteristics of social networks. It is hypothesized that having a larger proportion of intimate network members will be a protective factor, whereas having a larger proportion of drinking members in one's social network will be a risk factor. In the proposed study we will measure alcohol consumption, HIV risk sexual behaviors, and social networks characteristics, including drinking networks. We will use a new methodology to assess drinking and sexual behaviors in the prior month. Participants will be enrolled in the LIGHT study, a multisite NIMH supported preventive intervention project. The sample consists of inner-city minority adolescents and young adults at high risk for HIV infection from heterosexual contact.